Update index.html

[timohaver]

favourite -> favorite
colour -> color

[zombie]

Is there any discussion for doing this change?

favourite colour is sort of a theme in webext examples, see https://github.com/mdn/webextensions-examples/tree/master/favourite-colour, which is linked from some mdn pages, and all of that would need to change for consistency, while being careful not to break links.

Unless there are good reasons, I don't think these kinds of changes are worth the hassle.

[hamishwillee]

Well, the default language of the docs is US-English, and the changes are being done generally to match that across the wiki. So FWIW I think that if someone is willing to do these changes and make them carefully everywhere this is a good thing.

[Ryuno-Ki]

@zombie See #373

this needs other reviewer resolution

[sideshowbarker]

Closing this unmerged per #1357 (review)